When mmhmm cannot recognize an app window that it cannot "see", it may not display your screenshare slide.
App windows that appear minimized in your dock will not be available to screen share in mmhmm until they are restored. If you attempt to share your app window and minimize it, youll receive an error that states "Stream error: The stream has not provided any data after two seconds."
Maximize your app window to resolve this.
Virtual backgrounds in your video conferencing app
Zoom, Google Meet, and several other video conferencing platforms offer the ability to apply virtual backgrounds to your webcam. This will prevent your audience from being able to see your mmhmm slides.
To resolve this issue, check that the virtual backgrounds feature is turned off in your video conferencing app: